A STUDY OF HIGHLY ENERGETIC NEAR-BOTTOM OCEAN FLOW AT THE BASE OF THE SCOTIAN RISE (CURRENT, ABYSSAL)

• Other Authors: KELLEY, EDWARD A., JR., Florida State University
• Format: Text
• Language: unknown
• Subjects: Physical Oceanography; North Atlantic
• Online Access: http://purl.flvc.org/fsu/lib/digcoll/etd/3085834; http://fsu.digital.flvc.org/islandora/object/fsu%3A75321/datastream/TN/view/A%20STUDY%20OF%20HIGHLY%20ENERGETIC%20NEAR-BOTTOM%20OCEAN%20FLOW%20AT%20THE%20BASE%20OF%20THE%20SCOTIAN%20RISE%20%28CURRENT,%20ABYSSAL%29.jpg

Previous investigations disclosed a strong near-bottom equatorward contour-following flow at the base of the Scotian Rise near the 4,900 m isobath ((TURN)40(DEGREES)N, 62(DEGREES)W) which coexisted with a filament of relatively fresh cold water (termed the Cold Filament); energetic fluctuations with time scales 0(30-90 days) existed in current-meter data. A comparison is made of long (8-12 mos.) records of three near-bottom current-meters with satellite-derived frontal positions of Gulf Stream meanders and rings. The energetic fluctuations coincide with, and most probably result from, the movement of Gulf Stream meanders and rings. However, near the 4,500 m isobath, a 40-day energetic event indicates the apparent presence of topographic Rossby waves, which appear to fit Pedlosky's theory of a bottom-trapped baroclinic topographic Rossby wave resulting from destabilization of a sheared flow by topography. The evidence indicates that the strong equatorward contour-following flow near the 4,900 m isobath is decoupled from, and not part of, the Deep Western Boundary Current, which exists upslope of the 4,000 m isobath on the Scotian Rise. A search of archived hydrographic data of the western North Atlantic shows the Cold Filament to be an ubiquitous feature near the base of the Continental Rise from the Grand Banks Ridge (50(DEGREES)W) to 24(DEGREES)N. The Cold Filament is inferred to be a tracer for an equatorward contour-following flow. A sketch of the partial near-bottom circulation of the western North Atlantic is made based primarily on the Cold Filament; it agrees more closely with a model of the deep circulation by Wunsch and Grant than with a recent model by Hogg. A rough estimate of the dissipation of eddy kinetic energy as a result of the interaction of the Gulf Stream meanders and rings with the bottom indicates that this mechanism may account for roughly 50% of the energy input by the wind into the subtropical gyre of the western North Atlantic. Source: Dissertation Abstracts International, Volume: 45-04, Section: B, page: 1140. Thesis (Ph.D.)--The Florida State University, 1984.